[Variant:] "Please accept my resignation. I don’t care to belong to any club that will have me as a member".

As quoted in The Groucho Letters (1967) by Arthur Sheekman. The sentiment predates Marx by 61 years, however; it likely originated with John Galsworthy in The Forsyte Saga. In Part I, Chapter II, "Old Jolyon Goes to the Opera", it's said of Old Jolyon that, "He naturally despised the Club that did take him." after another refused him because he was in a trade.

No one is completely unhappy at the failure of his best friend.

From his book Groucho and Me. It is a variation of a maxim by 17th-century French nobleman François de La Rochefoucauld: "In the adversity of our best friends, we often find something that is not displeasing." (Maxim 99 from Reflections; or Sentences and Moral Maxims, 1665 edition.)

Here's to our wives and girlfriends... may they never meet![citation needed] (Variation on an old Royal Navy wardroom toast: "Wives and Sweethearts! May they never meet!"[citation needed])

From the moment I picked your book up until I laid it down I was convulsed with laughter. Someday I intend on reading it.

To S J Perelman about his book Dawn Ginsbergh’s Revenge (1929), as quoted in LIFE (9 February 1962)

I never forget a face, but in your case I'll be glad to make an exception.

I got $25 from Reader's Digest last week for something I never said. I get credit all the time for things I never said. You know that line in You Bet Your Life? The guy says he has seventeen kids and I say: "I smoke a cigar, but I take it out of my mouth occasionally"? I never said that.

I did a bond tour during the Second World War... We were raising money, and we played Boston and Philadelphia and most of the big cities. And we got to Minneapolis. There wasn't any big theater to play there, so we did our show in a railroad station. Then I told the audience that I knew a girl in Minneapolis. She was also known in St.Paul, she used to come over to visit me. She was known as "The Tail Of Two Cities." I didn't sell any more bonds, but eh... they didn't allow me to appear anymore.

Apparently said by Oscar Levant: "I knew Doris Day before she was a virgin" (as quoted in The Wit and Wisdom of Hollywood (1972) by Max Wilk).

Time flies like an arrow. Fruit flies like a banana.

No known citation to Marx. First appears unattributed in mid-1960s logic/computing texts as an example of the difficulty of machine parsing of ambiguous statements. Google Books. The Yale Book of Quotations dates the attribution to Marx to a 9 July 1982 net.jokes post on Usenet.

Outside of a dog, a book is man's best friend. Inside of a dog, it's too dark to read.

This may be original with Groucho, but the Quote Investigator mentions the earliest report found in a 1958 issue of Boy's Life magazine where it is attributed to Jim Brewer.

Politics is the art of looking for trouble, finding it everywhere, diagnosing it incorrectly, and applying the wrong remedies.

The original quotation ("Politics is the art of looking for trouble, finding it whether it exists or not, diagnosing it incorrectly and applying the wrong remedy.") belongs to Sir Ernest Benn; a first known citation reportedly appears in the Springfield (MA) Republican on July 27, 1930.

Some years back, after a childhood of preoccupation with comedy that led me to observing the styles of all the great comedians, I came to the conclusion that Groucho Marx was the best comedian this country ever produced. Now I am more convinced than ever that I was right. I can't think of a comedian who combined a totally original physical conception that was hilarious with a matchless verbal delivery. I believe there is a natural inborn greatness in Groucho that defies close analysis as it does with any genuine artist. He is simply unique in the same way that Picasso or Stravinsky are, and I believe his outrageous unsentimental disregard for order will be equally as funny a thousand years from now.
In addition to all this, he makes me laugh.

Groucho appeals on so many levels at once that you could go nuts trying to figure out whether it's the funny movement, the incomparable tone of voice, what he is saying, or that keenly witty face that hits you the hardest. I swear that if he never existed, we would sense a lack in the world of comedy, like that planet in the solar system that astronomers say Ought to be there.
For me he is The Master.

George Kaufman and I wrote a lot of funny lines for Groucho, some of which he occasionally used... but it was Groucho who by his innate sense of timing and his inimitable delivery, added the ingredient that brought the house down.